Managing a Virtual Machine Instance

ABSTRACT

The present invention relates to mechanisms for managing VM instances. More specifically, the mechanisms provide at least one VM instance in a resource pool. A configuration requirement is provided with respect to a virtual machine, the configuration requirement describing a first amount of application resources to be installed on the virtual machine. Based on the configuration requirement, a resource tree is built describing a dependency relation between the first amount of application resources. At least one VM instance corresponding to a sub-path of the resource tree is provided in the resource pool, where on each VM instance in the at least one VM instance there are installed application resources included in the sub-path.

BACKGROUND

Various embodiments of the present invention relate to virtual machines(VMs), and more specifically, to a method and apparatus for managing aVM instance.

With the development of computer hardware/software technologies andnetwork technology, virtual machines (VMs) are widely applied to variousrespects of people's work and life. By means of virtual machines, usersno more have to purchase high-performance computer devices and expensiveapplication resources (such as operating systems, middleware, middlewareconfigurations, databases, applications, etc.), do not have to installand test computer devices, and do not have to engage technicalprofessionals to install various needed application resources.

The user may request a virtual machine to a VM provider and specifyresources, such as computing resources, storage resources andapplication resources, should be installed on the virtual machine.Subsequently, the VM provider may allocate specific computing resourcesand storage resources from a resource pool and install neededapplication resources one after another according to configurationrequirements the user specifies.

Like the process of installing application resources on a physicalmachine, the VM provider also needs to install various applicationresources one after another, and since those application resources mightcontain a dependency relation between them, the VM provider shouldserially install those application resources one after another in anorder of the dependency relation. As the installation process involves acouple of configurations, the installation process of each applicationresource costs a certain amount of time, and as a whole it takes a longtime to generate a VM instance.

In order to reduce the wait time for users, there have been proposedtechnical solutions for provisioning in the resource pool VM instancesthat satisfy simple demands. However, these VM instances only have themost basic configurations, e.g., have a specific amount of CPUresources, memory resources and operating systems, which basicconfigurations do not satisfy ever-increasing special needs of massiveusers.

With the further complication of user needs, even if a VM instancehaving basic configurations has been obtained from the resource pool, ittakes a long time to install on the VM instance various applicationresources that are specified by the user. At this point, how to managethe resource pool in a more efficient way now becomes a focus ofattention.

SUMMARY

Therefore, it is desired to develop a technical solution capable ofeffectively managing VM instances in a resource pool, and it is desiredthe technical solution can provide a certain amount of VM instances in aresource pool in advance during normal running, so that when receiving auser request VM instances provided in advance may be allocated to theuser quickly so as to reduce the wait time for users and increase thequality of service. On the other hand, it is desired the technicalsolution can be compatible with the existing technical solution, so asto provide higher response efficiency without changing the existingtechnical solution as far as possible.

In one embodiment of the present invention, there is proposed a methodfor providing at least one VM instance in a resource pool, comprising:parsing a configuration requirement with respect to a virtual machine,the configuration requirement describing a first amount of applicationresources to be installed on the virtual machine; building, on the basisof the configuration requirement, a resource tree describing adependency relation between the first amount of application resources;providing in the resource pool at least one VM instance corresponding toa sub-path of the resource tree, wherein on each VM instance in the atleast one VM instance there are installed application resources includedin the sub-path.

In one embodiment of the present invention, there is proposed anapparatus for providing at least one VM instance in a resource pool,comprising: a processor; and a memory coupled to the processor, whereinthe memory comprises instructions which, when executed by the processor,cause the processor to: parse a configuration requirement with respectto a virtual machine, the configuration requirement describing a firstamount of application resources to be installed on the virtual machine;build, on the basis of the configuration requirement, a resource treedescribing a dependency relation between the first amount of applicationresources; provide in the resource pool at least one VM instancecorresponding to a sub-path of the resource tree, wherein on each VMinstance in the at least one VM instance there are installed applicationresources included in the sub-path.

In one embodiment of the present invention, there is proposed a computerprogram product comprising a computer readable storage medium having acomputer readable program for providing at least one virtual machineinstance in a resource pool stored therein, wherein the computerreadable program, when executed on a computing device, causes thecomputing device to: parse a configuration requirement with respect to avirtual machine, the configuration requirement describing a first amountof application resources to be installed on the virtual machine; build,on the basis of the configuration requirement, a resource treedescribing a dependency relation between the first amount of applicationresources; and provide in the resource pool at least one virtual machineinstance corresponding to a sub-path of the resource tree, wherein oneach virtual machine instance in the at least one virtual machineinstance there are installed application resources included in thesub-path.

By means of the method, apparatus, and computer program product of thepresent invention, a certain number of VM instances may be provided inthe resource pool in advance, and a desired VM instance provideddirectly or by a simple installation process when receiving a userrequest.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Through the more detailed description of some embodiments of the presentdisclosure in the accompanying drawings, the above and other objects,features and advantages of the present disclosure will become moreapparent, wherein the same reference generally refers to the samecomponents in the embodiments of the present disclosure.

FIG. 1 schematically depicts an exemplary computer system/server whichis applicable to implement the embodiments of the present invention;

FIG. 2 schematically depicts an exemplary cloud computing environment;

FIG. 3 schematically depicts abstraction model layers provided the couldcomputing environment (FIG. 2):

FIG. 4 schematically depicts a block diagram of a dependency relationbetween various application resources in a virtual machine:

FIG. 5 schematically depicts an architecture diagram of a technicalsolution for providing at least one VM instance in a resource poolaccording to one embodiment of the present invention:

FIG. 6A schematically depicts a flowchart of a method for providing atleast one VM instance in a resource pool according to one embodiment ofthe present invention, and FIG. 6B schematically depicts a flowchart ofa method for providing a VM instance according to one embodiment of thepresent invention;

FIG. 7 schematically depicts a block diagram of a resource treeaccording to one embodiment of the present invention;

FIG. 8 schematically depicts a block diagram of combining two resourcetrees according to one embodiment of the present invention;

FIG. 9 schematically depicts a block diagram of a resource treeaccording to one embodiment of the present invention; and

FIG. 10A schematically depicts a block diagram of an apparatus forproviding at least one VM instance in a resource pool according to oneembodiment of the present invention, and FIG. 10B schematically depictsa block diagram of an apparatus for providing a VM instance according toone embodiment of the present invention.

DETAILED DESCRIPTION

Some preferable embodiments will be described in more detail withreference to the accompanying drawings, in which the preferableembodiments of the present disclosure have been illustrated. However,the present disclosure can be implemented in various manners, and thusshould not be construed to be limited to the embodiments disclosedherein. On the contrary, those embodiments are provided for the thoroughand complete understanding of the present disclosure, and completelyconveying the scope of the present disclosure to those skilled in theart.

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 1, a schematic of an example of a cloud computingnode is shown. Cloud computing node 10 is only one example of a suitablecloud computing node and is not intended to suggest any limitation as tothe scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, cloud computing node 10 is capable ofbeing implemented and/or performing any of the functionality set forthhereinabove.

In cloud computing node 10 there is a computer system/server 12, whichis operational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 1, computer system/server 12 in cloud computing node 10is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 12 may include, but are not limitedto, one or more processors or processing units 16, a system memory 28,and a bus 18 that couples various system components including systemmemory 28 to processor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Referring now to FIG. 2, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 comprises one or morecloud computing nodes 10 with which local computing devices used bycloud consumers may communicate. The local computing devices may be, forexample, personal digital assistant (PDA) or cellular telephone 54A,desktop computer 54B, laptop computer 54C, and/or automobile computersystem 54N may communicate. Nodes 10 may communicate with one another.They may be grouped (not shown) physically or virtually, in one or morenetworks, such as Private, Community, Public, or Hybrid clouds asdescribed hereinabove, or a combination thereof. This allows cloudcomputing environment 50 to offer infrastructure, platforms and/orsoftware as services for which a cloud consumer does not need tomaintain resources on a local computing device. It is understood thatthe types of computing devices 54A-N shown in FIG. 2 are intended to beillustrative only and that computing nodes 10 and cloud computingenvironment 50 can communicate with any type of computerized device overany type of network and/or network addressable connection (e.g., using aweb browser).

Referring now to FIG. 3, a set of functional abstraction layers providedby cloud computing environment 50 (FIG. 2) is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 3 are intended to be illustrative only and embodiments of theinvention are not limited thereto. As depicted, the following layers andcorresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include mainframes (e.g.IBM® zSeries® systems); RISC (Reduced Instruction Set Computer)architecture based servers (e.g., IBM pSeries®, systems); IBM xSeries®systems; IBM BladeCenter® systems; storage devices; networks andnetworking components. Examples of software components include networkapplication server software (e.g., IBM WebSphere® application serversoftware); and database software (e.g, IBM DB2® database software).(IBM, zSeries, pSeries, xSeries, BladeCenter, WebSphere, and DB2 aretrademarks of International Business Machines Corporation registered inmany jurisdictions worldwide).

Virtualization layer 62 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers;virtual storage; virtual networks, including virtual private networks;virtual applications and operating systems; and virtual clients.

In one example, management layer 64 may provide the functions describedbelow. Resource provisioning provides dynamic procurement of computingresources and other resources that are utilized to perform tasks withinthe cloud computing environment. Metering and Pricing provide costtracking as resources are utilized within the cloud computingenvironment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal provides access to the cloud computing environment forconsumers and system administrators. Service level management providescloud computing resource allocation and management such that requiredservice levels are met. Service Level Agreement (SLA) planning andfulfillment provides pre-arrangement for, and procurement of, cloudcomputing resources for which a future requirement is anticipated inaccordance with an SLA.

Workloads layer 66 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation; software development and lifecycle management; virtualclassroom education delivery; data analytics processing; transactionprocessing; and VM instance management.

In one embodiment of the present invention, the technical solution formanaging VM instances according to various embodiments of the presentinvention may be implemented at workloads layer 66, so that the VMinstance management can be conveniently implemented in the cloudcomputing environment and further the VM provider's response time touser requests may be reduced. An application environment of the presentinvention has been illustrated above, whereas those skilled in the artshould understand various embodiments of the present invention mayfurther be implemented in any other type of computing environment thatis currently known or to be developed later.

FIG. 4 schematically shows a block diagram 400 of a dependency relationbetween various application resources in a virtual machine. Like theprocess of installing application resources on a traditional physicalmachine, in a virtual environment various application resources alsoneed to be installed one after another according to a dependencyrelation between those application resources. For example, in a virtualmachine 450 as shown in FIG. 4, an operating system 410 is the mostunderlying application resource which does not depend on otherapplication resources and thus can be directly installed on virtualmachine 450. Above operating system 410 there may further existmiddleware 420 and middleware configuration 430 for providing additionalsupport on the basis of operating system 410. Application/database 440may be top application resources which are installed only after thespecific operating system, middleware and middleware configuration areinstalled.

Therefore, when generating a VM instance, various application resourcesare installed one after another according to the dependency relation asshown in FIG. 4. When the user requests to install a large amount ofapplication resources and/or wants to install complex applicationresources, he/she, after submitting an application, has to wait fordozens of minutes or even longer before obtaining the VM instance.

With the complication of user needs, the amount of application resourcesto be installed also increases, and a dependency relation betweenvarious application resources gets more and more complicated. Generallyspeaking, there may exist a dependency relation as below: the middlewareis installed only after the operating system is installed, themiddleware configuration is executed only after the middleware isinstalled, the application/database is installed only after themiddleware configuration is executed, etc. Tables 1-4 belowschematically show examples of the operating system, the middleware, themiddleware configuration and the application/database, respectively.

TABLE 1 Example of Operating System No. Name Abbreviation 1 Red HatEnterprise Linux 64 bit for Intel RHEL64 2 Advanced InteractiveeXecutive 7.1 AIX71 3 Red Hat Enterprise Linux 64 bit for z systemRHEL64z . . . . . . . . .

TABLE 2 Example of Middleware No. Name 1 WebSphere Application Server8.5 2 WebSphere Application Server 7.0 3 Liberty 4 DB2 10 5 MySQL . . .. . .

TABLE 3 Example of Middleware Configuration No. Name 1 WebSphereApplication Server-Single Server 2 WebSphere ApplicationServer-Deployment Manager 3 WebSphere Application Server-Custom Node 4Liberty Server 5 DB2 Instance 6 MySQL instance . . . . . .

TABLE 4 Example of Application/Database No. Name 1 Mini storeapplication (Small-size app, No DB required) 2 DayTrader application(Middle-size app) 3 ERP application (Large-size app) 4 DayTrader DB anddata population (Middle-size database) 5 ERP DB and data population(Large-size database) . . . . . .

As shown in Tables 1-4 above, there are various levels of applicationresources, and there exist complicated dependency relations betweenthese application resources. The application resources in Tables 1-4 areexemplary only, and there may exist hundreds of and even moreapplication resources. Thereby, it is impossible to combine variousapplication resources and provide corresponding VM instances. Inaddition, since it is impossible to predict which type of VM instancemight be needed in future, VM instances that could be requested infuture cannot be provided in the resource pool in advance.

Although existing technical solutions can provide “bare” VM instances inthe resource pool or install VM instances of some underlying operatingsystems, this still does not satisfy user needs. At present applicationresources requested by a user are installed one by one only whenreceiving a request from the user. Therefore, the user has to spend alarge quantity of time on waiting for installation.

In view of various drawbacks in the prior art, the present inventionproposes a technical solution for providing at least one VM instance ina resource pool on the basis of configuration requirements of a user. Asshown in FIG. 5, this figure schematically shows a block diagram 500 ofa technical solution for providing at least one VM instance in aresource pool according to one embodiment of the present invention.Configuration requirements 510 schematically show configurationrequirements of a user. As shown in FIG. 5, the user wants to installRHEL 6.4, WAS 8.5, WAS Single and DayTrader App on a requested virtualmachine. On the basis of dependency relations between these applicationresources, a resource tree 520 may be built by parsing configurationrequirements 510. Resource tree 520 shows various application resourcesthat are installed one by one according to a path shown by arrows from aroot node “Start.”

Subsequently, on the basis of sub-paths in resource tree 520, VMinstances where application resources included in the sub-paths areinstalled may be provided in the resource pool 530. Specifically,regarding a sub-path “Start->RHEL 6.4->WAS 8.5->WASSingle->DayTraderApp,” for example, VM instances 532 including variousapplication resources along this sub-path may be provided (e.g., M VMinstances may be provided). For another example, regarding a sub-path“Start->RHEL 6.4->WAS 8.5,” VM instances 534 including variousapplication resources along this sub-path may be provided (e.g., N VMinstances may be provided). In this way, VM instances may be providedpertinently in view of the user's historical needs.

Note throughout the context of the present invention, the sub-pathrefers to a sub-path starting from the root node in the resource tree;the sub-path may start from the root node and ends at a leaf node, orstarts from the root node and ends at a non-leaf node. In resource tree520 as shown in FIG. 5, sub-paths may include: “Start->RHEL 6.4->WAS8.5->WAS Single->DayTraderApp,” “Start->RHEL 6.4->WAS 8.5,” etc.

In one embodiment of the present invention, there is provided a methodfor providing at least one VM instance in a resource pool, comprising:parsing a configuration requirement with respect to a virtual machine,the configuration requirement describing a first amount of applicationresources to be installed on the virtual machine; building, on the basisof the configuration requirement, a resource tree describing adependency relation between the first amount of application resources;providing in the resource pool at least one VM instance corresponding toa sub-path of the resource tree, wherein on each VM instance in the atleast one VM instance there are installed application resources includedin the sub-path.

In one embodiment of the present invention, the first amount ofapplication resources may include one or more application resources.When there exists only one application resource, the applicationresource does not depend on other application resource, so the resourcetree may only comprise nodes associated with the resource. When thereexists a plurality of application resources, the resource tree maydescribe application relations between the plurality of applicationresources.

Specifically, FIG. 6A schematically shows a flowchart 600A of a methodfor providing at least one VM instance in a resource pool according toone embodiment of the present invention. As shown in this figure, instep S602A, a configuration requirement with respect to a virtualmachine is parsed, the configuration requirement describing a firstamount of application resources to be installed on the virtual machine.The configuration requirement may be presented in various formats. Forexample, as shown in FIG. 5, configuration requirement 510 may berepresented in graph form; for example, the configuration requirementmay be represented in text form (RHEL 6.4->WAS 8.5->WASSingle->DayTraderApp); for example, the configuration requirement may berepresented in XML form; or even the configuration requirement may bedescribed in a natural language. When the configuration requirement isrepresented in a different form, it may be parsed on the basis of acorresponding algorithm, and further dependency relations between theplurality of application resources are obtained. Those skilled in theart may implement this according to concrete application environmentdemands, which is not detailed here.

In step S604A, a resource tree describing a dependency relation betweenthe first amount of application resources is built on the basis of theconfiguration requirement. The dependency relation refers to an orderwhich is followed when installing various application resources, and thepresent invention does not limit how the dependency relation isobtained. For example, the dependency relation may be obtained from anadditional configuration file, or the dependency relation may directlybe obtained from the configuration requirement where it is included inthe configuration requirement. Where the dependency relation isobtained, it may be described in a tree structure. For example, resourcetree 520 in FIG. 5 shows one example of the resource tree, wherein thedependency relation may be represented in arrows. For example, an arrowbetween nodes RHEL 6.4 and WAS 8.5 may represent the installation of WAS8.5 depends on RHEL 6.4, i.e., WAS 8.5 is installed only after RHEL 6.4is installed.

In step S606A, at least one VM instance corresponding to a sub-path ofthe resource tree is provided in the resource pool, wherein on each VMinstance in the at least one VM instance there are installed applicationresources included in the sub-path. For example, it is possible toprovide at least one VM instance with respect to each path of theresource tree or with respect to only one part of sub-paths of theresource tree. In the example as shown in FIG. 5, M VM instances 532 andN VM instances 534 may be provided, and no VM instance is provided withrespect to other sub-paths.

According to various embodiments of the present invention, not onlyinstances of a virtual machine that has been requested previously areprovided, but also instances of a virtual machine that has not beenrequested previously but might be requested later may be provided byproviding at least one VM instance corresponding to a sub-path of theresource tree. For example, a VM instance (on which RHEL 6.4 and WAS 8.5are installed) as shown by VM instance 534 in FIG. 5 may be provided.When the user requests a virtual machine where RHEL 6.4 and WAS 8.5 areinstalled, VM instance 534 in the resource pool may be directly returnedto the user. When the user requests a virtual machine where WASDeployment Manager is installed on the basis of WAS 8.5, only WASDeployment Manager needs to be installed on VM instance 534 but variousapplication resources do not have to be installed from the beginning.

Since the user need history can reflect future user needs to some extentand helps to predict VM instances that might be requested in future, bymeans of the technical solution of the present invention, the wait timefor users may be shortened greatly and the operating efficiency of thevirtual environment enhanced further.

In one embodiment of the present invention, the configurationrequirement describes a hardware resource need of the virtual machine,and the providing in the resource pool at least one VM instancecorresponding to a sub-path of the resource tree comprises: obtaining atleast one foundation VM instance that meets the hardware resource need;and installing application resources included in the sub-path to eachfoundation VM instance in the at least one foundation VM instance.

The configuration requirement may further include a desired hardwareresource need, for example, may specify the computing power of CPU, thesize of memory, network bandwidth and other parameters. Therefore, afoundation VM instance that meets the hardware need may be obtainedfirst, and then application resources included in the sub-path areinstalled one by one on the foundation VM instance. Although theinstallation process here costs a certain amount of time, theinstallation at this point is not triggered by a customer request but isa step for preparing a VM instance in advance, so the time beingconsumed will not affect the customer's wait time. In this manner, acertain number of VM instances may be provided for future customerrequests in the resource pool in advance, so the performance of thevirtual environment may be enhanced.

In one embodiment of the present invention, the installing applicationresources included in the sub-path to each foundation VM instance in theat least one foundation VM instance comprises: installing applicationresources included in the sub-path one by one on the basis of thedependency relation. For example, the implementation may take an orderof operating system, middleware, middleware configuration andapplication/database.

In one embodiment of the present invention, there is further comprised:obtaining process parameters associated with the installation ofapplication resources included in the sub-path; and determining thenumber of the at least one VM instance on the basis of the processparameters.

Those skilled in the art may understand the user does not like waiting.When the installation time lasts only for 5 minutes, it is acceptable tothe user; when the installation time last for 1 hour, however, it mightbe unacceptable to the user. Therefore, it may be determined, on thebasis of process parameters associated with the installation process,how many VM instances will be provided in the resource pool. Forexample, regarding a VM instance that is installed for a long time, alarger number of VM instances may be provided; while regarding a VMinstance that is installed for a short time, a less number of VMinstances may be provided. At this point, even if the resource pool doesnot contain a VM instance being requested, the user does not mindwaiting for 5 minutes.

Only one respect of the installation process has been illustrated above.Since the installation process might involve complicated operations, theprocess parameters may include various respects of contents. In oneembodiment of the present invention, the process parameters comprise atleast one of: the number of times that a virtual machine correspondingto a sub-path of the resource tree is requested, and the time forinstalling application resources included in the sub-path.

It should be understood in the user need history, if the user frequentlyrequests a VM instance where some application resources are installed,then this type of VM instance might be requested again. Thus, regardinga VM instance that is requested for many times, a larger number of VMinstances may be provided; while regarding a VM instance that isrequested for fewer times, a less number of VM instances may beprovided. Only two examples of the process parameters have beenillustrated above. Those skilled in the art may further adopt othermethod on the basis of a concrete application environment. For example,if it is considered the installation process will occupy a large amountof computing resources in the virtual environment, then the amount ofoccupied computing resources may further act as one respect of theprocess parameters.

In one embodiment of the present invention, the amount of the at leastone VM instance is proportional to the process parameters. Detaileddescription has been presented above to how to provide a correspondingamount of VM instances on the basis of the number of requests and theinstallation time. On the basis of the principle, those skilled in theart may define a concrete calculation equation as an applicationenvironment demands.

For example, the amount of VM instances may be calculated as a functionof the number of requests in a past time period:

Amount of VM instances=Number of requests/a  Equation 1

wherein a is a constant number, and those skilled in the art may adjusta value of a on the basis of status of the virtual environment.

For example, the number of VM instances may be calculated as a functionof the installation time:

Number of VM instances=Installation time/b  Equation 2

wherein b is a constant number, and those skilled in the art may adjusta value of b on the basis of status of the virtual environment.

For another example, the number of VM instances may be calculated on thebasis of both the number of requests and the installation time:

Number of VM instances=Number of requests×installation time/c  Equation3

wherein c is a constant number, and those skilled in the art may adjusta value of c on the basis of status of the virtual environment.

Or the number of VM instances may be calculated on the basis ofEquations 1-3 or a combination of only one part thereof. For example, amaximum, a minimum or a mean of Equations 1-3 may be selected.

On the basis of the method described above, the number of times the VMinstance corresponding to the sub-path in the resource tree is requestedand the installation time may be collected, and it can be calculated howmany VM instances should be provided in the resource pool. These datamay be added to the resource tree, and by traversing the resource tree,responding VM instances can be provided. FIG. 7 schematically shows ablock diagram 700 of a resource tree according to one embodiment of thepresent invention. As shown in this figure, an attribute (installationtime, number of requests, amount) may be added to each node. As shown inFIG. 7, the value in an ellipse over each node represents a processparameter associated with the installation of an application resourcerepresented by the node: a numeral 710 represents the installation time(4 minutes), and a numeral 720 represents the number of requests (1000requests). The value in a circle above each node represents the numberof to-be-provided VM instances which is calculated on the basis of theprocess parameter. Specifically, a numeral 730 represents the number ofto-be-provided VM instances (40).

By traversing the resource tree as shown in FIG. 7, it may be clearlydetermined which types of VM instances need to be provided, and it maybe determined how many VM instances need to be provided with respect toeach type. For example, a node RHEL 6.4 represents 40 VM instances whereRHEL 6.4 is installed need to be provided; a node DayTrader represents 9VM instances where RHEL 6.4, WAS 8.5, WAS Single and DayTrader areinstalled need to be provided.

In one embodiment of the present invention, there is further comprised:parsing a second configuration requirement with respect to a secondvirtual machine, the second configuration requirement describing asecond amount of application resources to be installed on the secondvirtual machine; building, on the basis of the second configurationrequirement, a second resource tree that describes a dependency relationbetween the second amount of application resources; and combining thesecond resource tree with the resource tree according to acorrespondence relation between the first amount of applicationresources and the second amount of application resources.

Since the need history may include many configuration requirements, eachneed may be parsed one by one or only one part of needs may be parsed,so as to obtain a plurality of resource trees. By combining theplurality of resource trees, the user's various needs with respect to VMinstances may be extracted gradually, and these needs are recorded in atree resulting from the combination.

Specifically, FIG. 8 schematically shows a block diagram 800 ofcombining two resource trees according to one embodiment of the presentinvention. For example, a first resource tree 810 is built by parsing afirst configuration requirement, and a second resource tree 820 is builtby parsing a second configuration requirement. As shown by arrows A andB in FIG. 8, nodes “RHEL 6.4” in first resource tree 810 and in secondresource tree 820 have a correspondence relation, and nodes “WAS 8.5” infirst resource tree 810 and in second resource tree 820 have acorrespondence relation, so nodes “RHEL 6.4” in the two trees may becombined and nodes “WAS 8.5” in the two trees may be combined, therebyobtaining a resource tree 830.

FIG. 8 merely illustrates an example of combining resource treesgenerated from two configuration requirements. When there are aplurality of configuration requirements, a plurality of resource treesfrom the plurality of configuration requirements are combined into aresource tree as shown in FIG. 9 by using the method described withreference to FIG. 8. FIG. 9 schematically shows a block diagram 900 of aresource tree according to one embodiment of the present invention. LikeFIG. 7, in FIG. 9 the value in an ellipse over each node represents aprocess parameter associated with the installation of applicationresources represented by the node, and the value in a circle over eachnode represents the number of VM instances to be provided. By traversingthe resource tree as shown in FIG. 9, VM instances corresponding to eachsub-path of the resource tree may be provided. For example, 40 VMinstances where RHEL 6.4 is installed may be provided; 32 VM instanceswhere AIX 7.1 is installed may be provided, and 60 VM instances whereRHEL 6.4 and WAS 8.5 are installed may be provided, etc.

In one embodiment of the present invention, the application resources atleast comprise at least one of: an operating system, middleware,middleware configuration, a database system, and an application. Thoseskilled in the art may understand with the development of computertechnology, there might be a growing variety of application resources.In the context of the present invention, examples of applicationresources are merely illustrated. According to the principle of thepresent invention, application resources may include various resourcesthat are currently known or to be developed later.

In one embodiment of the present invention, the method of the presentinvention is executed periodically. For example, a configurationrequirement from a user, the number of times the VM instance isrequested, as well as the installation time may be monitored in realtime, and the resource tree is updated in real time using these data, soas to manage the resource pool on the basis of the latest data.

In one embodiment of the present invention, there is provided a methodfor providing a VM instance, comprising: obtaining a configurationrequirement with respect to a virtual machine as contained in a userneed; and in response to the existence ofa VM instance that satisfiesthe configuration requirement in a resource pool, providing the VMinstance, wherein the resource pool is a resource pool according to amethod described in the present invention.

On the basis of the foregoing principle, various types of VM instancesmay be provided in the resource pool. Thus, when later receiving arequest from a customer, first it is looked up in the resource poolwhether or not there exists a VM instance satisfying the configurationrequirement; if yes, the VM instance satisfying the configurationrequirement is provided directly.

In one embodiment of the present invention, there is further comprised:in response to no existence of a VM instance that satisfies theconfiguration requirement in the resource pool, searching in theresource pool for a VM instance that satisfies at least one part of theconfiguration requirement, installing to the VM instance applicationresources associated with other part of the configuration requirement,and providing the VM instance.

When in the resource pool there is no VM instance satisfying theconfiguration requirement, a VM instance that best approaches theconfiguration requirement may be found, and other application resourcesrequested by the user are installed on the VM instance, whereby therequested VM instance is obtained rapidly.

Now returning to FIG. 6B, this figure schematically shows a flowchart600B of a method for providing a VM instance according to one embodimentof the present invention. In step S602B, a configuration requirementwith respect to a virtual machine as contained in a user request isobtained. In step S604B, it is judged whether or not in the resourcepool there is a VM instance satisfying the configuration requirement: ifyes, the flow proceeds to step S608B, otherwise to step S606B. In stepS606B, other needed application resources are installed to a VM instancesatisfying one part of the configuration instance, and the VM instanceis provided in step S608B.

Detailed illustration is presented now to details to step S606B by meansof a concrete example. Returning to FIG. 7, suppose currently only VMinstances associated with the resource tree as shown in FIG. 7 areprovided in the resource pool. When the user requests a virtual machinewhere RHEL 6.4 and WAS 7.0 are installed, since the resource poolcontains no VM instance satisfying this configuration requirement, therequested VM instance cannot be provided to the user directly. At thispoint, a VM instance where RHEL 6.4 is installed may be selected fromthe resource pool, and then WAS 7.0 is installed on this VM instance soas to satisfy the user need. Note since the installation time for WAS7.0 lasts for only 8 minutes, compared with the existing technicalsolution for installing a plurality of application resources from thebeginning, the technical solution of the present invention greatlyshortens the wait time for users.

Various embodiments implementing the method of the present inventionhave been described above with reference to the accompanying drawings.Those skilled in the art may understand that the method may beimplemented in software, hardware or a combination of software andhardware. Moreover, those skilled in the art may understand byimplementing steps in the above method in software, hardware or acombination of software and hardware, there may be provided an apparatusbased on the same invention concept. Even if the apparatus has the samehardware structure as a general-purpose processing device, thefunctionality of software contained therein makes the apparatus manifestdistinguishing properties from the general-purpose processing device,thereby forming an apparatus of the various embodiments of the presentinvention. The apparatus described in the present invention comprisesseveral means or modules, the means or modules configured to executecorresponding steps. Upon reading this specification, those skilled inthe art may understand how to write a program for implementing actionsperformed by these means or modules. Since the apparatus is based on thesame invention concept as the method, the same or correspondingimplementation details are also applicable to means or modulescorresponding to the method. As detailed and complete description hasbeen presented above, the apparatus is not detailed below.

FIG. 10A schematically shows a block diagram 1000A of an apparatus forproviding at least one VM instance in a resource pool, comprising: aparsing module 1010A configured to parse a configuration requirementwith respect to a virtual machine, the configuration requirementdescribing a first amount of application resources to be installed onthe virtual machine; a building module 1020A configured to build, on thebasis of the configuration requirement, a resource tree describing adependency relation between the first amount of application resources; aproviding module 1030A configured to provide in the resource pool atleast one VM instance corresponding to a sub-path of the resource tree,wherein on each VM instance in the at least one VM instance there areinstalled application resources included in the sub-path.

In one embodiment of the present invention, the configurationrequirement further describes a hardware resource need of the virtualmachine, and providing module 1030A comprises: a foundation obtainingmodule configured to obtain at least one foundation VM instance thatmeets the hardware resource need; and an installing module configured toinstall application resources included in the sub-path to eachfoundation VM instance in the at least one foundation VM instance.

In one embodiment of the present invention, the installing modulecomprises: a first installing module configured to install applicationresources included in the sub-path one by one on the basis of thedependency relation.

In one embodiment of the present invention, there are further comprised:a parameter obtaining module configured to obtain process parametersassociated with the installation of application resources included inthe sub-path: and a determining module configured to determine thenumber of the at least one VM instance on the basis of the processparameters.

In one embodiment of the present invention, the process parameterscomprise at least one of: the number of times that a virtual machinecorresponding to a sub-path of the resource tree is requested, and thetime for installing application resources included in the sub-path.

In one embodiment of the present invention, the number of the at leastone VM instance is proportional to the process parameters.

In one embodiment of the present invention, there are further comprised:a second parsing module configured to parse a second configurationrequirement with respect to a second virtual machine, the secondconfiguration requirement describing a second amount of applicationresources to be installed on the second virtual machine; a secondbuilding module configured to build, on the basis of the secondconfiguration requirement, a second resource tree that describes adependency relation between the second amount of application resources;and a combining module configured to combine the second resource treewith the resource tree according to a correspondence relation betweenthe first amount of application resources and the second amount ofapplication resources.

In one embodiment of the present invention, the application resourcescomprise at least one of: an operating system, middleware, middlewareconfiguration, a database system, and an application.

FIG. 10B schematically shows a block diagram 1000B of an apparatus forproviding a VM instance according to one embodiment of the presentinvention. Specifically, there is provided an apparatus for providing aVM instance, comprising: an obtaining module 1010B configured to obtaina configuration requirement with respect to a virtual machine ascontained in a user request; and a first providing module 1020Bconfigured to, in response to the existence ofa VM instance thatsatisfies the configuration requirement in a resource pool, provide theVM instance, wherein the resource pool is a resource pool according to amethod described in the present invention.

In one embodiment of the present invention, there is further comprised:a second providing module 1030B configured to, in response to noexistence of a VM instance that satisfies the configuration requirementin the resource pool, search in the resource pool for a VM instance thatsatisfies at least one part of the configuration requirement, install tothe VM instance application resources associated with other part of theconfiguration requirement, and provide the VM instance.

By means of the methods and apparatuses of the present invention, acertain number of VM instances may be provided in the resource pool inadvance, and a desired VM instance may be provided directly or by asimple installation process when receiving a user request.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java, Smalltalk, C++ or the like,and conventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to best explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

1. A method for providing at least one virtual machine instance in aresource pool, comprising: parsing a configuration requirement withrespect to a virtual machine, the configuration requirement describing afirst amount of application resources to be installed on the virtualmachine; building, on the basis of the configuration requirement, aresource tree describing a dependency relation between the first amountof application resources; and providing in the resource pool at leastone virtual machine instance corresponding to a sub-path of the resourcetree, wherein on each virtual machine instance in the at least onevirtual machine instance there are installed application resourcesincluded in the sub-path.
 2. The method according to claim 1, whereinthe configuration requirement further describes a hardware resource needof the virtual machine, and the providing in the resource pool at leastone virtual machine instance corresponding to a sub-path of the resourcetree comprises: obtaining at least one foundation virtual machineinstance that meets the hardware resource need; and installingapplication resources included in the sub-path to each foundationvirtual machine instance in the at least one foundation virtual machineinstance.
 3. The method according to claim 2, wherein the installingapplication resources included in the sub-path to each foundationvirtual machine instance in the at least one foundation virtual machineinstance comprises: installing application resources included in thesub-path one by one on the basis of the dependency relation.
 4. Themethod according to claim 1, further comprising: obtaining processparameters associated with the installation of application resourcesincluded in the sub-path; and determining the number of the at least onevirtual machine instance on the basis of the process parameters.
 5. Themethod according to claim 4, wherein the process parameters comprise atleast one of: the number of times that a virtual machine correspondingto a sub-path of the resource tree is requested, and the time forinstalling application resources included in the sub-path.
 6. The methodaccording to claim 5, wherein the number of the at least one virtualmachine instance is proportional to the process parameters.
 7. Themethod according to claim 1, further comprising: parsing a secondconfiguration requirement with respect to a second virtual machine, thesecond configuration requirement describing a second amount ofapplication resources to be installed on the second virtual machine;building, on the basis of the second configuration requirement, a secondresource tree that describes a dependency relation between the secondamount of application resources; and combining the second resource treewith the resource tree according to a correspondence relation betweenthe first amount of application resources and the second amount ofapplication resources.
 8. The method according to claim 1, wherein theapplication resources comprise at least one of: an operating system,middleware, middleware configuration, a database system, and anapplication. 9-10. (canceled)
 11. An apparatus for providing at leastone virtual machine instance in a resource pool, comprising: aprocessor; and a memory coupled to the processor, wherein the memorycomprises instructions which, when executed by the processor, cause theprocessor to: parse a configuration requirement with respect to avirtual machine, the configuration requirement describing a first amountof application resources to be installed on the virtual machine; build,on the basis of the configuration requirement, a resource treedescribing a dependency relation between the first amount of applicationresources; and provide in the resource pool at least one virtual machineinstance corresponding to a sub-path of the resource tree, wherein oneach virtual machine instance in the at least one virtual machineinstance there are installed application resources included in thesub-path.
 12. The apparatus according to claim 11, wherein theconfiguration requirement further describes a hardware resource need ofthe virtual machine, and wherein the instructions further cause theprocessor to: obtain at least one foundation virtual machine instancethat meets the hardware resource need; and install application resourcesincluded in the sub-path to each foundation virtual machine instance inthe at least one foundation virtual machine instance.
 13. The apparatusaccording to claim 12, wherein the instructions further cause theprocessor to: install application resources included in the sub-path oneby one on the basis of the dependency relation.
 14. The apparatusaccording to claim 11, wherein the instructions further cause theprocessor to: obtain process parameters associated with the installationof application resources included in the sub-path; and determine theamount of the at least one virtual machine instance on the basis of theprocess parameters.
 15. The apparatus according to claim 14, wherein theprocess parameters comprise at least one of: the number of times that avirtual machine corresponding to a sub-path of the resource tree isrequested, and the time for installing application resources included inthe sub-path.
 16. The apparatus according to claim 15, wherein thenumber of the at least one virtual machine instance is proportional tothe process parameters.
 17. The apparatus according to claim 11, whereinthe instructions further cause the processor to: parse a secondconfiguration requirement with respect to a second virtual machine, thesecond configuration requirement describing a second amount ofapplication resources to be installed on the second virtual machine;build, on the basis of the second configuration requirement, a secondresource tree that describes a dependency relation between the secondamount of application resources; and combine the second resource treewith the resource tree according to a correspondence relation betweenthe first amount of application resources and the second amount ofapplication resources.
 18. The apparatus according to claim 11, whereinthe application resources comprise at least one of: an operating system,middleware, middleware configuration, a database system, and anapplication. 19-20. (canceled)
 21. A computer program product comprisinga computer readable storage medium having a computer readable programfor providing at least one virtual machine instance in a resource poolstored therein, wherein the computer readable program, when executed ona computing device, causes the computing device to: parse aconfiguration requirement with respect to a virtual machine, theconfiguration requirement describing a first amount of applicationresources to be installed on the virtual machine; build, on the basis ofthe configuration requirement, a resource tree describing a dependencyrelation between the first amount of application resources; and providein the resource pool at least one virtual machine instance correspondingto a sub-path of the resource tree, wherein on each virtual machineinstance in the at least one virtual machine instance there areinstalled application resources included in the sub-path.
 22. Thecomputer program product according to claim 21, wherein theconfiguration requirement further describes a hardware resource need ofthe virtual machine, and wherein the computer readable program furthercauses the computing device to: obtain at least one foundation virtualmachine instance that meets the hardware resource need; and installapplication resources included in the sub-path to each foundationvirtual machine instance in the at least one foundation virtual machineinstance.
 23. The computer program product according to claim 21,wherein the computer readable program further causes the computingdevice to: obtain process parameters associated with the installation ofapplication resources included in the sub-path; and determine the amountof the at least one virtual machine instance on the basis of the processparameters.
 24. The computer program product according to claim 21,wherein the computer readable program further causes the computingdevice to: parse a second configuration requirement with respect to asecond virtual machine, the second configuration requirement describinga second amount of application resources to be installed on the secondvirtual machine; build, on the basis of the second configurationrequirement, a second resource tree that describes a dependency relationbetween the second amount of application resources; and combine thesecond resource tree with the resource tree according to acorrespondence relation between the first amount of applicationresources and the second amount of application resources.